Weathering is a natural process used to define the slow degradation of materials exposed to the weather. The rate of weathering varies within timber species, but depends most of all on the microclimatic conditions. Even if a lot of research is dedicated to studies on the weathering mechanisms of diverse materials the comprehensive understanding and detailed models are hardly available for wood surfaces. This research is a part of activities within the Round Robin test, the common initiative of the COST Action FP1006, where 28 sets of samples were exposed in 18 locations in Europe and Brazil. Two types of experimental samples (“thin” and “thick”) were prepared from one log of Norway spruce tree (Picea abies L.) and were exposed for short (28 days) and long term (one year) weathering process. The list of surface characterization methods applied for assessment of RR test samples includes: colour CIE Lab, VIS, NIR and MIR spectra, imaging, gloss, XRF and roughness. Two alternative NIR spectrophotometers were selected and intensively tested with this work, including laboratory and portable devices. NIR spectroscopy was used for identification of the chemical changes in wood due to weathering. Besides routine spectra interpretation, novel approaches for calculation of weathering index were performed. Such algorithms allowed direct comparison of the effect of geographical location on the intensity of wood degradation.